REVIEW: QR-E 250W ELECTRIC BOOSTER BICYCLE MOTOR AND B60i AND B70 BATTERY

[Charlie Pendejo]

Thanks yet again. It makes sense the 4" version would be stronger than the 2.75" I'm using. Two reasons not to switch:

(a) It's too clean and sensible, not something one would call "crackpot" or "harebrained." It'd feel too out of character.
(b) And oh yeah, there's only about 3.55" between chainrings. I could probably fit a 3" hinge in there, but wouldn't expect sizing up 1/4" to give that much more juice.

Adding supplementary pull from the rear seemed like far & away the simplest thing to try, so I tried it. First I bolted a short bit of stretchy strap + buckle to the motor assembly:

And when I'd finally added enough pressure for the motor to retain grip in boost mode, it was with a daisy-chained pair of reusable zip ties, hooked through a slot in a steel adapter which holds the rear fender:

I may try to refine this a bit, perhaps replacing the zip ties with a strap and routing between fender & seat stay... but at least I've arrived at something that has worked well for a quick jaunt around the neighborhood. This weekend I'll aim to get out with the kiddo for a longer 15+ mile shakeout ride.

Today's other surprise was only getting my new (purchased a year ago but unused until now) S2 switch to work very sporadically, like 1 try in 10. Old one still works, though it got damaged in touring 2 summers ago - it needed resoldering and I lost the front face of the "box" which surrounds the switches. I'll troubleshoot later, and at least have enough parts that I should be able to put together one complete & functional S2. Or maybe this is a sign from the universe to try and put together my own control including a boost switch that can stay on once toggled.

 

[EMGX]

You can make your own switch for ~$10 with a 6ft usb micro extension (make sure it has data wires, not just charging) and switches of your choice. The extension wires are very small gauge so soldering can be a challenge.

 

[Charlie Pendejo]

I may well do that, and having assembled some amp & preamp kits over the decades, soldering's more in my wheelhouse. Do you know where I can find a wiring diagram / description?

Another connector fairly near the control end would add a lot of convenience: I could simply disconnect the cable before removing the handlebars, as part of folding & bagging the bike. That probably would've saved my original S2 from getting damaged when I packed the bike to bring on a train or bus.

Poked around both Amazon and AliExpress looking for handlebar-mountable switches with both a latching switch (for boost) and a momentary switch (for mode). They exist, often intended for headlight + a horn, but most are either for 22mm mountain bars (I have 25.4 drops) or cost more than I want to spend.

 

[EMGX]

Blueberry posted the wiring info which I followed, it's pretty simple.
I didn't want one of the handlebar mounted switches because they limit placement. Just ordered some rocker switches to try those out, cost $3.99 including shipping for 5 of them on Amazon. I wanted latching so I could activate regen without having to hold the button, just blipping a switch on/off works for changing power mode. I'm going to wire a brake cut off switch in line with the boost button for safety because I have one but that probably isn't that important.

 

[EMGX]

I made up another switch using latching rocker switches. I think I'll stick with this and may or may not add a brake cut out.
The 6 ft usb micro extensions I have (came two in a pack, for ~$8 back when I bought them) have 4 wires, red (not used), black (common ground), green (corresponds to the mode/regen switch) and white (corresponds to the power switch). I'm not sure if all manufacturers use the same color coding so YMMV.

 

[EMGX]

they say B70 batteries can be used with the Pro. I've got it to power up with "information" totally disconnected but I haven't done extensive testing yet. I think it'll work though. Best I can tell "information" is a logic level signal from the controller back to the battery pack that tells the indicator lights to turn on?

Side note, I tried connecting up a 10s3p battery to the Pro to see if the extra few volts from another cell in series would make it go faster, but actually it refuses to turn on with a battery voltage above 38V.

Blueberry, if you still check in on this thread, where did you see that they (Qiroll?) say B70 batteries can be used with the Pro? I did message them and all they messaged back is the generic statement that the H70 is for the Pro and the B70 is for the Mute. I ended up buying a Pro and did try the B70 battery from my Mute just to see if it works, which it did but it was just a short test run. I'm planning on riding the Mickelson trail in South Dakota next week (weather permitting) and taking the B70 battery along as a power bank and as a standby for the Qiroll but don't want to run it on low voltage if it could overheat or otherwise damage the motor.